Patent GB-808411-A (GB)
Title: Improvements in or relating to moisture exchangers for gaseous media
IPC: F24F6/06
Filed: 1955-02-03
Abstract: 808,411. Conditioning air. MUNTERS, C. G. Feb. 3, 1955 [Feb 3, 1954], No. 3183/55. Class 137 [Also in Groups XII and XIII] A moisture exchanger for changing the the moisture content of a gas stream, e.g. of air, by means of a second gas stream, e.g. of air, comprises a housing with a separate inlet, a separate outlet and a separate duct for each gas stream and a moisture transfer body formed with a multitude of passageways or open channels and containing a hygroscopic material or substance, the moisture transfer body being moved in the housing along a closed path and each of the gas streams being led through the passageways or channels of the moisture transfer body when they are positioned in the ducts, the directions of movement of the moisture transfer body and the gas streams being parallel and opposite to one another during the passage of each gas current from the inlet to the outlet of their respective ducts and the moisture transfer body being formed of a number of spaced contact units, each unit filling up the cross-section of the ducts and a plurality of the units moving simultaneously in each respective duct while being traversed in series by the gas stream therein. As shown in Fig. 2 a housing 10 has intake openings 12 and 16 for primary air to be dried and for secondary air respectively, with corresponding outlets 14 and 18. Each of the air currents is conveyed through the apparatus by a separate fan 20, 22, respectively and connected as shown. In the housing the primary air traverses a duct 24 and the secondary air a duct 26. An endless flexible belt 28, e.g. of rubber, passes round four rolls 30 one of which is driven at a low speed by a geared motor so that contact units 36 rigidly secured to the belt are slowly moved in a substantially rectangular path of travel. Each contact unit comprises a frame of channel-section metal enclosing a number of wool foils or sheets of a hygroscopic material, e.g. a paper in which wool fibres or fibres of other highly hygroscopic material have been incorporated or a material which has a covering or coating of a hydroscopic material such as fine particles of silica gel. Alternate sheets of the material may be plane and corrugated and the spacing between the plane sheets is less and 2-3 mm. The contact units are divided into groups by partitions 48 also mounted on the belt 28 and comprising flaps 54 which are open during passage through ducts 24 and 26 and which are closed during passage through intermediate ducts 38 and 40. The flaps are made of a light material so that they open or close in response to the variations in pressure produced on the housing. In operation the primary air, e.g. the air from a room conditioned during summer, having a temperature of about 20‹ C and a moisture content of about 80 per cent is dried during passage through the housing whereby its moisture content is reduced to about 20 per cent and its temperature increased to about 33‹C. The temperature of the dried air may be lowered before return to the room. The secondary air, e.g. atmospheric air having initially a temperature of about 30‹C. and a moisture content of about 60 per cent, is heated by a heater 56 to about 60‹C. reducing its moisture content to about 15 per cent. The moisture absorbed in the duct 24 from the primary air stream is thus transferred to the secondary air stream by the individual contact units as they rotate. A small portion of the dried primary air may be allowed to pass upwardly through the passage 38 to cool by evaporation the contact units passing therethrough and minimize the transfer of heat from the secondary air to the dried primary air. Make-up for this portion of the primary air is admitted through line 58 and inlet 60. The contact units may comprise a filamentary mass having hygroscopical properties constructed as described in Specification 748,311. In a modification the arrangement may be such that the contact units traverse a circular instead of a rectangular path of travel. In a further modification the contact units are in the form of individually separate units, and the transition passage between the ducts carrying the primary and secondary air streams are dimensioned so as to be capable of containing one contact unit at a time in a position parallel to the position of the units in the ducts. The rotating arrangement is such that each contact unit in the ducts is moved a distance equal to the thickness of one unit, pistons being provided simultaneously to move the units in the transition zones into the ducts and a unit from each duct into a transition zone. Specifications 770,201, 808,413 and 808,414 also are referred to.